Synthesis of Isooctenyl Alcohols from Diisobutylene via Chlorination

Isooctenyl alcohols were prepared from hydrolysis of diisobutylene monochlorides which were obtained by chlorination of diisobutylene. Analysis and identification of diisobuylene monochloride and isooctenyl alcohol and hydrolysis of the diisobutylene monochloride to isooctenyl alcohol in the presence of alkalis and solvents were studied. The following results were obtained.(1) Structures of the products were determined by the comparison of their IR and NMR spectra with those of authentic compounds. The diisobutylene monochloride contained 1-chloro-2-neopentyl-2-propene, cis-1-chloro-2, 4, 4-trimethyl-2-pentene, trans-1-chloro-2, 4, 4-trimethyl-2-pentene and 3-chloro-2, 4, 4-trimethyl-1-pentene, and the isooctenyl alcohol contained 2-neopentyl-2-propene-1-ol, cis-2, 4, 4-trimethyl-2-pentene-1-ol, trans-2, 4, 4-trimethyl-2-pentene-1-ol and 2, 4, 4-trimethyl-1-pentene-3-ol.(2) Reaction conditions in the presence of alkalis were studied. Among the alkalis used, sodium carbonate, sodium bicarbonate and calcium hydroxide gave favorable results, and the optimum pH value was in the range of 8∼11. When a strong alkali such as sodium hydroxide was used, favorable results were obtained by keeping pH at 8∼10.(3) DMSO was found to be one of most effective solvents in that the rate of hydrolysis was high and primary isooctenyl alcohols were obtained in high selectivity.(4) The kinetic studies showed that hydrolysis of monochloride was of the SN2 type.(5) Examination of the product composition during hydrolysis in DMSO showed that secondary monochloride changed to primary isooctenyl alcohols by isomerization. The reaction path of four isooctenyl chlorides, which were contained in the monochloride, was discussed.